Hello again. Still strugle with languages. I managed to output the content translated. But are there any way to change a culture key dynamicly? Basicly it must be saved during the user session. So I am not using the system setting method in oficial documentation because I afraid that it will affect other visitors of a site.
Actually I got it. You can just redifine this setting via session in a snipped.
$_SESSION['cultureKey']='en'; //for example
And after next refresh it will be redifined. For my particular task it is just fine. Because it will be used only on language change.
Sorry Actually I was mistaking the solution. I have found a better and working way to do it at
https://forums.modx.com/thread/88465/refresh-cache-set-culturekey-and-refresh-page-when-clicking-a-link
The right code that still work on modx 3 is
<a href="[[~[[*id]]? &cultureKey=`en`]]">English</a>
And the same for other languages,